The present invention pertains to an endless belt for use with a heavy duty track vehicle, such as a crawler-type vehicle, a tractor or equipment having tracks over wheels that provide both ground support and tractive effort.
The propulsion system found on heavy duty vehicles consists of a pair of longitudinally spaced apart wheel structures which are arranged on opposite sides of the vehicle chassis which is driven by a pair of endless, substantially inextensible belts, each having an inner surface and an outer surface. The inner surface is provided with a series of longitudinally spaced members which guide the track relative to driving and tracking wheels forming part of the wheel structures. The outer surface of the belt is formed of a plurality of longitudinally spaced tread members that provide traction to the vehicle when travelling on various ground conditions.
One such belt structure is illustrated and described in U.S. Pat. No. 5,279, 378 issued Jan. 18, 1994 to Caterpillar Inc. Similar tracks are also illustrated and described in U.S. Pat. No. 5,005,922 issued Apr. 9, 1991 to Edwards and Co. and U.S. Pat. No. 5,984,438 issued Nov. 16, 1999 to Tsunoda et al.
These endless belts, although inextensible, are subject to bending as they engage the necessary supporting wheels such as drive and idler wheels or rollers. As the belt passes around and contact these wheels, they are subject to stress and it is noted that the greatest stress occurs at the base of the tread member or its junction with the top surface of belt. Belt slitting is also noted whenever the construction of the belt consists of a tread member and a guide member in the same vertical plane.
Vibration is also a problem with these types of belts.
It is an object of the present invention to provide a geometry to an endless belt of a heavy duty track propelled vehicle which greatly reduces the stress exerted on the belt, especially during its bending occurrence when driven. This is achieved by precisely locating the relative positions of the tread members on the outer surface of the belt to that of the guide members on the inner surface of the track.
It is another object of the present invention to provide an arrangement of tread members that will result in a reduction of vibration.
The present invention therefore relates to an endless belt for use with a heavy duty track vehicle comprising:
an elongated endless body made of polymeric material, said body having a longitudinal direction, an outer surface and an inner surface;
a plurality of longitudinally spaced guide members integrally formed to said inner surface extending transversely to the longitudinal direction at mid-section of said body and defining first valleys between adjacent guide members; and
two rows of longitudinally spaced tread members integrally formed to said outer surface; the tread members of a first of said rows being longitudinally offset relative to the tread members of a second of said rows; each said tread member of said first and said second rows having an inner edge area located at a mid-section of said body and extending transversely to a longitudinal direction of the belt; said tread members defining second valleys between adjacent inner edge areas of each said rows and an outer edge area; said tread members defining a series of pitches on said outer surface of said track wherein a pitch is defined as including a tread member of the first row and an adjacent tread member of the second row; each said inner edge area of said tread members being in vertical alignment with a corresponding one of said guide members on said inner surface of said body and parallel to the corresponding one of the guide members;
wherein two longitudinally spaced guide members are provided on the inner surface for each pitch of said outer surface;
wherein each pitch on said belt differs from another pitch in value;
wherein each first valley is in vertical alignment with corresponding second valley so that flexing of said track, when bending, occurs in said first and second valleys where thickness of the body is at its minimum.
Other objects, advantages and features of the present invention will become more apparent upon reading of the following non restrictive description of preferred embodiments thereof, given by way of example only with reference to the accompanying drawings.